Data storage media are commonly used for storage and retrieval of data, and come in many forms, such as magnetic tape, magnetic disks, optical tape, optical disks, holographic disks, cards or tape, and the like. Magnetic tape media remains economical for storing large amounts of data. For example, magnetic tape cartridges, or large spools of magnetic tape, are often used to back up data in large computing centers. Magnetic tape cartridges also find application in the backup of data stored on smaller computers such as desktop or notebook computers.
In magnetic tape, data is typically stored as magnetic signals that are magnetically recorded on the tape surface. The data recorded onto magnetic tape is typically organized along “data tracks,” and transducer heads are positioned relative to the data tracks to write data to the tracks or read data from the tracks. A typical magnetic data storage tape includes several data tracks within a data band. Other types of linear media, such as optical tape, magneto-optic tape, holographic tape, and other tape media formats can also make use of data tracks.
Servo patterns refer to signals or other recorded marks on a data storage medium that are used for tracking purposes. The servo patterns are typically recorded on servo tracks of a linear tape medium in order to provide reference points relative to the data tracks. A servo controller interprets detected servo patterns and generates position error signals. The position error signals are then used to adjust the lateral distance of the transducer head relative to the data tracks so that the transducer head is properly positioned along the data tracks for effective reading and/or writing of the data to the data tracks.
In some types of magnetic tape, the servo patterns are stored in specialized bands on the medium, called “servo bands.” The servo bands are separated from data bands, and may include several servo tracks within a given servo band. Magnetic tape often includes a plurality of servo bands, with data bands located between the servo bands.